Treatment of vanadium ore.



L. F. VOGT.

TREATMENT 0F VANADIUM ORB.

APPLIGATIUN FILED Nov. 26, 1913.

3 Patented Feb. 23, 1915.

CoA/ENTRA 71's of? @Hou/vo Oms [a] /W/x W/m Fume/N5 coMPou/va 50u/BLE 50a/UM S/ILTS so 1 reslduei Washingsy In such cases 'the-'dry mixtures or ores and luorm bearing .minerals may be treated, as a preliminary step, by adding crude acid to the mixture or by moistening the mass and exposing it to `the action of acid fumes of 4any suitable character,'-such -for',example as those driven off during the secondl step of my regular processor in any other Way Which Will result in the decomposition 'of the fluorin compounds and the generation -of hydroiuoric acid. Or such generation may be effected in a separate receptacle" and the acid there formed conducted into the vanadium ore mass.

Second etape-The V'mixture or paste of vanadium bearing material and sulfuric acideither with or without the addition of iuori'n bearing compounds-is lallowed to stand or digest and slowly disintegrate, until the reaction between the acid and the vanadium compound has proceeded as far as it will Without the application of heat. The past-y mixture of sulfates, ore residue and acid is. then charged into a furnace, or other suitable appliance, and'subjected to lsufficiently intense and suiiciently long continued heat to complete the reaction be- Y tween the vanadium and other metals in the mass and the sulfuric acid, and also to d-rive oif the volatile constituents of the ore The heating is lcontinued until most, but not all,,of the residual free acid has also been driven off; the amount of free acid' content left being determined by the original composition of the ore, and theresuitant nature and amount of the impurities to be removed iin subsequent stages of the operation. l v

In order to recover the acid which is driven olf' during the latter lstages of lthe roasting operation the fumes or stack gases, `which contain the excess of acid, .largely in the form of sulfuric anhydrid, 'fare led through coke. towers 'or other suitable form of scrubber, containing lovv pressure steam jets or sprays of water. The sulfuric anhydrid is 'thus once more converted to sul-A furic acid, which can be used again infthe treatment of a fresh mass of vanadium ore. 50

Or in 'some cases a portion of 'the stack fumes, containingy the sulfuric anhydrid fumes may be directly utilized, as already explained-,- in 'the preliminary vtreatment of 'the mixed mass or ore and fluorin bearing material. In any case the recovery `'of the sulfuric acid or sulfuric anhydrid fumes vby one or the other of the above' described operations is very desirable and limportant as it effects a large daily saving in acid consuinption,- and thus considerably reduces the lcost of my improved process of vanadium o're treatment;

Third stepf-Theroasted cake of crust obltained in the second step is next digested, boiled, or lixiviated with water, or with acid, has been dissolved out. Y liquor thus obtained contains the vanadium has been disintegrated and the vanadium and the soluble metallic salts formed in the first two steps of the operation together with the unvolatilized excess of sulfuric The acid and other metals as sulfatos or a solution of the oxids in sulfuric acid; and the residual sludge contains the Waste mineral or ganguc of the ore. The liquor and sludge are separated from .one another by decantation, or by filtering or filter pressing or in any other suitable manner, and the filter residue or Waste lsludge is washed repeatedly with `Warm acidulated. Water to free it from all soluble vanadium content. The first-filter Washings are added to the vanadium filtrate liquor, andthe final diluted Washings are stored separately for use with thegsulfuric acidin the rst-step treatment of a fresh body of vanadium ore, as already described.

This manner'of handling the filter Washings or Wash water insures the 'complete and effective Washing of the filter residue or sludge, avoids undue dilution of the main filtrate' liquor, obviates any necessity for evaporating or concentrating the filterwashings to vsmall volume'to enable them to be used, and thus eifects a very decided economy in the operation.

Fourth step- The filtrate obtained in the thirdstep contains, as already pointed out, a considerable excess of free sulfuric acid. The next step in my improved operation is to heat this liquor and add to it a suiicient amount of .iron to precipitate the copper and arsenic. The amount of iron added depends of course on the percentage composition of the filtrate. In the case of the ore which I amnow treating by my improved process I indl that it is desirable to add about `two parts of iron for each part-by Weight-of vanadium contained in the filter solution The treating or roasting which form a part of the second step of my process mustalso be controlled and governed by the composition of the ore in such mannerthat aftersuiiicient iron vhas .been added to precipitate the copper and arsenic as just described the filter liquor will still contain at least 5 per cent. of free acid. Under such circumstances the addition of the iron precipitates first the copper and then the arsenic in the form 4of a sludge, and reduces the vanadium present to a lower oxid salt which is still retained in solution by the presence ofthe free acid. The vanadium liquor is then separated from the copper arsenic sludge precipitate by decantation or filtering or filter pressing, the lter sludge being Well washed as before with Warm acidulated water to free it as far as possible from soluble vvanadium salts. The filter stant stirring until maca' v cial product which may be treated for the recovery of copper.

Fifth step-fthe filtrate or filter liquor obtained in the fourth step is next heated-to boiling and a dilute solution of soda ash or caustic soda is slowly added with cona sufficient amount of alkali has been introduced to neutralize practically all of the residual' free acid in the ltrate. When this has been done the vanadium content of the filter liquor is pre-y cipitated along with a portion ofthe iron added in the preceding step as ferrous vanadate. When this action is complete, as determined by suitable control tests, the ferrous vanadate sludge or precipitate is separated from the solution by decantation or hltration as in previous operations, and is washed free 'from the soluble sulfates and sulfur compounds. lt is then. dried and set aside for subsequent treating the character of which is determined by the original constitution of the ore.

Sixth ste .-(a) lf the ore treated is reasonably yree from phosphorus, or if so little phosphorus is contained in `the vanadium precipitate obtained in step 5 as to make its removal unnecessary, the washed and dried ferrous vanadate issnext ignited and roasted and thereby converted into a mixture of iron and vanadium oxid suitable for use in the preparation of ferro vanadium or other purposes. (b) the vanadate precipitate contains an objectionable amount of phosphorus l first treat it to remove the phosphorous salts. As a first step in this sub-operation l roast or fuse the dry and finely divided vanadium compound obtained in 'step 5 with common salt (sodium chlorid with the addition of sodium or otassium nitrate, and soda ash) sodium car onate if required. The amount of alkali used varies somewhat with the composition of the ,ores-and the resultant composition of the ferrous vanadate--but sufficient should be used in all cases to obtain practically all of the vanadium in the form of sodium vanadate. ln the treatment of the particular ore with which I am now working I have found, for example, that about 15 parts of salt for every 4 parts by weight of vanadium gives good The phosphorus present is also converted into soluble sodiumy phosphate. edmass is then, if necessary, ground or pulverized and lis next digested with hot water (e'), which dissolves out the vanadates and phosphates; due-consisting tered 0H. The filtrate will be more or less alkaline. Add to the filtrate sufficient of a mostly of iron oxid--is fil num -phosp his refused with refusion, redissolved and retreated just as But if from its ores which results.

The roast- (d) and the insoluble resisolution of aluminum or aluminum salt, (e), ysuch as sodium aluminate, to precipitate the phosphorus contained in the ltrate, which phosphorus will separate as alumihate upon the addition of sufiicient acid (f) to nearly neutralize the solution. -This precipitate is separated as before by decantation or filtration (g). The filtrate liquor and filter washings, which contain most of thevanadium, is heated to boiling/.and suflicient of the filtrate liquor obtained in lstep 5-which contains a large proportion of ferrous sulfate-is added (it) to once more precipitate the vanadium as ferrous vanadate. ln ,this operation care must be taken to aifoid any acidity of the solutions and if such acidity exists it must be neutralized by the addition of soda ash or caustic soda solution. The ferrous vanadate precipitate is then separated from the solution by decantation or filtration (i), as before, washed, dried and ignited (j) to convert it into iron and vanadium oxids.

ln the precipitation of the phosphorus as aluminum phosphate a small amount of vanadium may be carried down and retained with the phosphorus precipitate.l If there is sufficient vanadium so retained to warrant recovery, the washed precipitate salt and the product of the described in the preceding paragraph. The

second aluminum phosphate filtrate is then added to the first, or treated separately as before with the ferrous sulfate filtrate liquor obtained in step 5, tolprecipitate the vanadium as ferrous vanadate.

rlhe advantages of my improved process for the treating of vanadium ores,par ticularly those difficult of reduction by ordinary processes,will now be readily understood by those skilled in the art; to whom it will be obvious also that .various detail mdifications may be made in the op-y erations above specifically described lwithout departing from the substance of my i11- vention.

`What l claim' as new, and desire to secure by Letters-Patent is 1. The `process of extracting vanadium consists in treating the ore with an excess of sulfuric acid, roasting the aciduated mass until most but not all of theA acid excess has been driven 0H, digestin the roasted mass with water to obtain an acid solution of the vanadium and metal salts formed by the action of the sulfuric acid, adding iron to said acid solution to precipitate copper and' arsenic, and then neutralizing the excess of acid in the filtrate to precipitate thevanadium in the form of ferrous vanadate, substantially as described.

.2. The process with an excess of sulfuric acid to form sulioo of extracting vanadlum from its ores consisting in treating the ore "fates,I roasting the treated mass until most but not all of the uncombined acid has been driven and: the rest of the acid from the roasted mass, adding iron to the acid solution to precipitate copper arsenic, and then neutralizing the excess of acid in the filtrate to precipitate ferrous vanadate from the same, substantially as described.

3. The process of extracting vanadium from its ores consisting in first mixing the ore with an acid compoundy capable of breaking up the silicates and silicious matter in the ore, then subjecting the mixture to the action of heat to drive off most but not all of the uncombined acid, then treating the roasted mass with water to obtain an acid solution of the vanadium and other soluble sulfates, then adding iron to this Solution in sufficient quantity to precipitate the copper and arsenic, and then adding an alkali, to neutralize the remaining free acids in the filtrate and precipitate ferrous vanadate therefrom, substantially as described.

In a process of extracting vanadium, the sub-process consisting in roasting or fusing ferrous vanadate precipitate containing phosphorus with salt thereby converting the vanadium and phosphorus con* tent of the precipitate into soluble sodium compounds, next dissolving out the soluble off, dissolving out the soluble sulfates i rfrom the roasted compounds and adding aluminum salt to the solution to precipitate phosphorus therefrom in the form of aluminum compounds, and finally precipitating vanadium from the filtrate by adding ferrous sulfate thereto.

5. The process of extracting vanadium from ores containing a high percentage of phosphorus which consists in first treating the ore so as to obtain the vanadium therefrom in the form of ferrous vanadate, then fusing said vanadate with common salt so as to convert the ferrous vanadate and the phosphorus salts mixed therewith into soluble sodium vanadate and sodium phosphate, then extracting said soluble sodium salts mass by digestion with hot water, then in the solution so obtained pre- .cipitating the phosphorus therefrom by adding an aluminum salt solution, and then ytreating the sodium vanadate filtrate with a solution of ferrous sulfate to precipitate the vanadium in the form of ferrous vanadate, substantially as described. A

In testimony whereof, I have signed this specification in the presence of two subscribing witnesses.

LOUIS F. VOGT.

JOHN F. CARMICHAEL. 

